Methods of producing photographic image carriers provided with precipitants for coloring dyes



ing matter passing-"over from the matrices I Patented July 19,

iA r-EN r-v,OFFICE This invention relates to thejproduction of phq oz ph n se riet P ov ded-W h me- A cipitants" for coloring dyes. In order to obtain welldefined and correctly colored photographic pictures, it is necessary, to precipitate. the color- (washed out reliefs) onto thecarriers, as rapidly and completely as possible,' in the form of insoluble lac.

,,The patents owned by the Hess Ives Co. (such the year 1918) deal in general with the precipitating or all kinds of dyes (acid and basic) in the form of insoluble lacs. In particular, there is there disclosed the use of chromium compounds for acid coloring matter (alizerine dyes), According to his Swiss patent numbered 123,332, Arx employscuprous thiocyanate for this purpose. At a considerably-earlier date there had beenemployed, more particularly in conjunction with the use of basic dyestuffs, the mordants commonly used in the dyeing trade, such as tan- ..nin, tartar emetic (antimony compound), and

- the like. Tannin has already been employed. as

' a precipitantby Dr. Traube in the Uvachrome process, but the lac compounds obtained in this manner are not perfectly insoluble. Evenbut slight solubility, however, gives rise to lack of definition in the finished pictures. Moreover, these tannin lacs are not fast to light.

Recently substanceshave been found which are capable of forming dye lacs which are not only absolutely insoluble but also faster to light than those hitherto obtainable. These substances-are the complex acids, such as phosphotungstic acid, antimonotungstic acid, silicotungstic acid, and the like, which are likewise already extensively used in dye works. They are described in the German patents numbered 286,467, 289,878, and 403,002, and also in the Enzyklopadieder technischen Chemie by Prof. Dr. F. Ullmann, Vol. V.

To a certain extent, however, these complex acids also possess the inconvenient 'property of. breaking up hydrolyticaliy, with the evolution of qcleavage products of a dark andgenerally blueish color. Moreover the prints produced oncarriers of which the gelatine layer contains substances 9 of this description become rapidly: darker in the finished state. Thus for example a gelatine layer prepared with phosphotungstic acidsoon becomes ..blue when exposed to the air, and consequently the picture printed thereon also becomes muddled in its colours, and the colourless portions become toned. I t

On the other hand, a carrier the layer of which as the Austrian Patent No. 74,223 dating from I 1934, Serial No, 106,128. Divided and this ap 'Yplicationloctober"30, 1934, Serial-No. 750,688. in Aus r J Julrz i 3 V V i 'sz ciaim (crioii sr is treated with the additionof mordants such as m example cuprous iodide have the disadvantage that the basic dyestufi is not precipitated 'in'the form of lac on printing. The definition of the picture consequentlysufiers, and the al-' 5 ready applied dyestufi sinks very readily to a lower level at the next printing operation. Moreover, these metallic mordants turn brown in the presence of the slightest traces of hydrogen sulphide, with the formation of black copper sul- 1o phide.

I Certain organic acids likewise possess great precipitating, power for basic dyes, without exhibiting thefabove-mentioned drawbacks when employed for the production of coloredprints. This is more particularly true of 5 (beta)-oxynaphthoic acid, which, when introduced into the gelatine layer of an image carrier, precipitates the applied dye base in the form of lac, in precisely the same manner as the above-mentioned lac-formers, without subsequently forming colored cleavage products, and without givingrlse to subsequent darkening of the picture. The same behaviour is also exhibited by the 'homologues of this acid, derivatives of naphthylamine and of naphthol. g

The difilculty in the way of introducing these substances into a gelatine solution, however, consists in the fact that all these substances precipit'ate not only basic dyestuffs in an insoluble 80 .form, but likewise also gelatine, albumen, rubber, y

and the like. 7

If there be added to a gelatine solution a solu-' tion of one oi? the precipitants named above, the same becomes at once, precipitated in the form of a pastyinsoluble mass.

A way has now been found, with the aid of certainneutral salts such as for example ammonium acetate, of bringing complex acids and gelatine into solution in a single working phase. 40

.To the gelatine solution embodying an addl- 'tion of. ammonia there is added the solution of one of thesecomplexacids, such as for example 'silicotungstic acid. In this case precipitation of the gelatine no longer takes place. There is then -It has moreover not proved possible hitherto to find a pre-treatment for the printing matrices (washing out reliefs) made from cellulose, which does not color at all with the employment of basic dyestuffs, and which does not part with the bulk of the coloring matter absorbed to the gelatine layer of the carrier furnished with precipitants. This slight quantity of coloring matter absorbed by the preliminary treatment is likewise brought during printing on to the gelatine layer of the image carrier, and intensifies the smudging eflect of the bleeding out dyer If, however, the hardened gelatine layer of a carrier in which the precipitants, for example ,9 (beta) -oxynaphthoic acid, are present be coated with a top layer, for example of non-hardened, soft gelatine to which, if desired, a very slight quantity of these precipitants can also be added, the coloring matter derived from the bleeding and from the tinting of the matter used for the preliminary treatment of the matrix is absorbed by this top layer. If, after the finishing of the picture, this top layer be removed, it will be clear without further explanation thatthe coloring matter absorbed by it is also rendered of no efi'ect on the image. V V

Since this top layer must be so readily removable that for example a bathing of the picture in warm water or gentle rubbing of the same with a pad of cotton-wool suflices therefor, there must be used for the same materials which do not homogeneously combine with the gelatine layer of the carrier, or substances will be added thereto'which prevent such combining (for example the. addition of ox-gall to the soft gelatine of the top layer) and cause ready detachability (for example additions of gum arabic, dextrine, sugar, and the like).

We claim:

l. A method of producing a can'ier for imbibition dye prints in which the gelatine layer is provided with precipitants for the dyestufls, consisting in introducing ammonia into a solution of gelatine, adding a dye mordant in the form of .a complex acid thereto, adding acetic acid in amount suflicient to react with the ammonia to form ammonium acetate, and utilizing the resultant solution for making a carrier film.

2. A method as defined in claim 1, in which the 3 (beta) oxynaphthoic acid is the complex acid employed.

' RICHARD oscnorr'.

KARL POKORNY. 

